Dead latch construction



Oct. 18, 1966 R, H. swANsoN 3,279,836

DEAD LATCH CONSTRUCTION Filed Feb. 24, 1964 2 Sheets-Sheet l IN VEN TOR.

R13/Ano H. SWAMSON Oct. 18, 1966 R. H. swANsoN DEAD LATCH CONSTRUCTION 2 Sheets-Sheet 2 Filed Feb. 24, 1964 .N mw aw mN r E WA 5N 5 H www o nm M EH YN H B 0 m H R m United States Patent O 3,279,s36 DEAD LATCH CUNSTRUCTION Richard H. Swanson, Fullerton, Calif., assignor to Emhart Corporation, a corporation of Connecticut Filed Feb. 24, 1964, Ser. No. 346,823 8 Claims. (Cl. 292-169) This invention relates to a dead latch bolt mechanism, and more particularly to a latch bolt mechanism which incorporates a dead latch for preventing forcible disengagement of the main latch bolt from an associated strike plate until normal retraction of the main latch bolt is desired.

In latch bolt mechanisms which incorporate a dead latch or auxiliary bolt in combination with a main latch bolt, the -auxiliary bolt is depressed upon engagement of the auxiliary bolt with a strike plate, while the main latch bolt is extended and projected into the keeper in the strike plate. In its depressed position, the auxiliary bolt prevents retraction of the main latch bolt and forcible release of the main latch bolt from the keeper in the strike plate, as by insertion of a knife blade or the like between the door and the strike plate. The main latch bolt may only be retracted and freed from the keeper upon rotation of one of the door knobs to permit retraction of said main latch bolt by a retractor slide.

The present invention takes into account the fact that attempted forcible release of the main latch bolt by unauthorized persons always occurs in the absence of retracting movement of the retractor slide. Therefore, the present invention incorporates an auxiliary 4bolt dog which, when the `auxiliary bolt is depressed, is always biased by the main latch bolt spring to its dogging position, the dog being moved to its undogged or released position to permit depression of the main latch bolt only upon movement of a dog mount which pivotally supports` the dog. The requisite movement of the dog mount cannot occur until retracting movement of the retractor slide.

Other dead latch bolt mechanisms presently available are complicated, include a substantial number of component parts, and are often difcult to assemble. In contrast thereto, the device of the present invention is characterized by its simplicity, and its components are limited in number, relatively inexpensive to manufacture, and easy to assemble.

Easy operation of a lock set is greatly enhanced by minimizing the frictional contact surface between components which are slidable relative to each other during the operation of said lock set. In the lock set of the present invention the retractor slide and the housing for the retractor slide are constructed so as to greatly reduce the area of engagement therebetween. Thus, frictional interengagement of the slide housing and the retractor slide has been reduced without sacrificing the strength and durability of these components, and a strong, rugged, but easily operable mechanism for alternately locking and retracting the main latch bolt has thus been provided.

It is, therefore, an object of the present invention to provide a latch bolt mechanism incorporating a dead latch in which the dead latch or auxiliary bolt dog is always biased to its clogging position to prevent forcible depression of the main latch bolt exteriorly of the closed door,

said locking dog being movable to its undogged or released position only upon sirnultaneous extension of both the -auxiliary bolt and the main latch bolt or, when the auxiliary ybolt is depressed, upon retracting movement of the retractor slide.

Another object of the present invention is to provide a latch bolt mechanism incorporating a dead latch in which the dog of the dead latch is mounted upon a latching dog mount for pivotal movement between dogging and un- 3,279,836 Patented Oct. 18, 1966 ICC dogged positions and in which the locking dog mount must move inwardly to elect movement iof the dog to its undogged position.

Another object of the invention is the provision of a latch bolt mechanism incorporating a strike engaging dead latch or auxiliary bolt which, upon depression, permits movement of the locking dog to its dogging position, but which thereafter performs no function in the movement of the locking dog between its dogging and undogged positions so long as the main bolt is engaged in the keeper of said strike.

A further object of the invention is to provide a latch bolt mechanism incorporating a dead latch having a dog pivotable by the main latch bolt spring into dogging position for engagement with the latch case upon depression of the auxiliary bolt.

A further object of the invention is the provision of a lock set mechanism in which the retraction of the main bolt and the auxiliary bolt is enhanced by a reduction in the area of frictional engagement between the retractor slide and the spindle housing.

Another object of the invention is to provide a latch bolt mechanism incorporating a dead latch having a dog pivotally supported upon a mount for pivotal movement of the dog between dogging and undogged positions, inward movement of the dog mount being required for movement of the locking dog to its undogged position when the associated auxiliary bolt is retracted.

A further object of the invention is a latch bolt mechanism incorporating a dead latch characterized by a construction and arrangement of components having a relatively long service life, and wherein the relative movement of such components is so slight that frictional Wear of the components is substantially negligible.

Another object of the invention is the provision of a latch bolt mechanism incorporating a dead latch wherein the dog is mounted upon a dog mount for pivotal movement between its dogging and undogged positions.

Other objects and features of the present invention will be readily apparent to those skilled in the .art from the following specification and accompanying drawings wherein is illustrated one form of the invention and in which:

FIG. l is an isometric view of the lock set mechanism of the present invention;

FIG. 2 is a transverse, cross-'sectional view taken along the broken line 2 2 of FIG. l;

FIG. 3 is a cross-sectional view taken on the line 3 3 of FIG. 2; p

FIG. 4 is a longitudinal cross section taken along the broken line 4 4 of FIG. 1;

FIG. 5 is a view similar to FIG. 4 but in less detail and showing external retractive force being applied to the main latch bolt;

FIG. 6 is a cross-sectional view taken on the line 6 6 of FIG. 1;

FIG. 7 is a cross-sectional view taken on the line 7 7 of FIG. 6;

FIG. 8 is an exploded isometric View of the latch housing or case and the components therein; and

FIG. 9 is an isometric view of the head of the main latch bolt.

. Referring to the drawings, I show a l'ock set 10i. The lock set 10, as is well known to those skilled in the art, is disposable in operative relatio-nship with a door (not shown). The lock set 10 includes a slide housing or cas'e 12 located in a transverse opening in the door, and a latch bolt housing or case 14 located in a longitudinal bore in the edge of the door.

Projecting from the outermost end of the latch bolt case 14 is a main latch bolt 16 to which is secured an inwardly and longitudinally extending latch bolt extension 18, the innermost end of which is engaged for retraction by a retractor slide 20.

For purposes of convenience in description, and not by way of limitation, the terms exterior and interior are herein used to refer to the exterior and interior sides, respectively, of the door with which the lock set is associated.

The slide housing 12, which operatively supports the retractor slide 20, is substantially C-shaped in side elevation, the interior and exterior sides of the housing 12 being constituted by an interior side plate 24 and an exterior side plate 26. The housing 12 includes a plurality of transversely extending mounting lugs 28, which project into a plurality of mating mounting openings 30 in. the plates 24 and 26, the mounting lugs 28 being staked to secure the plates 24 and 26 in position.

VA plurality of inwardly oriented guide members 32 is provided upon the side plates 24 and 26, a pair of the guide members 32 being provided adjacent each of the upper and lower edges of the plates 24 and 26, the guide members 32 of the interior plate 24 being juxtaposed to the guide members 32 of the exterior plate 26 and being spaced therefrom to define upper and lower longitudinally extending tracks within which the retractor slide 2t) is reciprocatable. The relatively thin inner end faces of the guide members 32 provide minimum contact areas with the sides of the retractor slide 20, thereby minimizing frictional drag upon the retractor slide 20.

The construction of the retractor slide also minimizes the areas of frictional engagement between the retractor slide 2t? and the slide housing 12. More particularly, the retractor slide 20 is constituted by a pair of thin, vertically disposed, longitudinally extending plates 34 and 36 which, respectively, include pairs of laterally projecting cam faces 38 and 40. The cam faces 33 and 40 are spaced from the upper and lower edges of the plates 34 and 36 to permit unobstructed relative sliding movement between the inner end faces of the guide members 32 and the upper and lower edge portions of the plates 34 and 36.

The cam faces 38 and 40, which are engageable upon their outer surfaces for reciprocation of the retractor slide 20, are iirmly held in position by a pair of anchor legs 42 which are formed by reversely bending lugs on the inner extremities of the plates 34 and 36. The extremities of the pairs of reversely bent anchor legs 42 abut against the inner, laterally extending surfaces of the cam faces 38 and 40. Each plate 34 and 36 includes a longitudinally and outwardly extending portion constituting a bolt extension retractor 44 having a T-head 46 for `engaging the latch bolt extension 18, as will be seen.

The plates 34 and 36 constituting the retractor slide 20 are suitably secured together, as by spot welding, and it is noted that the relatively thin upper and lower edges of the plates 34 and 36 constitute the only frictional engagement between the retractor slide 20 and the slide housing 12, thereby facilitating sliding of the retractor slide 20 within the slide housing 12.

The retractor slide 20 is biased outwardly by a retractor compression spring 50 which is interposed between a seat 52 on the slide 20 and a spring seat 48 in the housing 12, thereby constantly biasing the retractor slide 2t) outwardly in a longitudinal direction. Reciprocation of the retractor slide 20 is eected by engagement of the cam faces .38 and 40 by a pair of half-round retractor .cams 54 provided upon a tubular `spindle constituting an interior rollback 56, and also .by additional retractor cams provided upon a tubular exterior spindle or rollback 58, which will be described hereinbelow.

The interior rollback S6 extends laterally of the slide housing 12 and is rotatably carried within a laterally extending, cylindrical boss 66 integral with the interior Vside plate 24. Movement of the interior rollback S6 out of the housing 12 is limited by engagement between the ind ner vertical surface of the side plate 24 and a pair of stops, not shown, provided upon the interior rollback 56. By limiting movement of the rollback 56'outwardly of the slide housing 12, proper alignment is assured between the retractor cams S4 and the cam faces 38.

Rotation of the interior rollback 56 in one direction engages one of the cams 54 with one of the cam faces 38 to move the retractor slide 20 inwardly, and rotation of the interior rollback 56 in the opposite direction causes the other retractor cam 54 to engage the other cam face 38 to also move the retractor slide 20 inwardly. Thus, rotation in either ydirection of an interior door knob 61 keyed to the rollback 56 moves the retractor slide 20 inwardly and rotation in either direction of an external knob 63 keyed to the rollback 58, also moves the retractor slide 26 inwardly.

The exterior rollback 58 is constituted by a transversely extending tubular sleeve which rotatably iits within a cylindrical boss 64 integral with the exterior plate 26. Movement of the exterior rollback 58 out of the slide housing 12 is limited by engagement between the inner, vertical surface of the exterior side plate 26 and a pair of stops, not shown, provided upon the exterior rollback '58 so that a cam face 63 of the rollback 58 is properly aligned with one of the cam faces 46 of the retractor slide 2th for reciprocatable movement thereof. Reciprocation of the slide 20 may also be accomplished by a cam provided upon a tubular lock actuated spindle or rollback 72 which is rotatably carried within the hollow interior of the tubular exterior rollback 58. The cams 68 and 70 are constituted by half-round, outwardly formed portions of the exterior rollback 58 and the lock actuated rollback 72, respectively. The cam 79 i5 engageable with the exterior rollback 58 to prevent the lock actuated rollback 72 from moving outwardly of the slide housing'lZ, consequently assuring proper alignment of the cam 70 with one of the cam faces 4t! of the retractor slide 2t).

The bosses 6G and 64 of the interior and exterior side plates 24 and 2e, respectively, project beyond the interior and exterior surfaces of the door with which they are associated, and usual decorative rosette plates (not shown) are engaged upon exterior threads 74 and 76 of the bosses 66 and 64 to retain the spindle housing 12 within the transverse opening in the door.

The pair of door knobs '61 and 63 are slidable over the projecting ends of the interior and exterior rollbacks 56 and 58 and are keyed to the interior and exterior rollbacks 56 and 58, respectively, by an internal knob catch 78 and an external knob catch Sii. Each of the catches 78 and 80 is constituted by an arcuately shaped member 81 carried within the hollow interior of its rollback and made of resilient material tooutwardly spring against and tightly engage the interior of the rollback.

Each ofthe knob cat-ches '78 and 80 includes a but-ton 79 (FIG. 2) which protrudes through a suitable opening in the wall of the respective rollback, to constrain the knob catch against movement relative to the rollback and also to engage the usual tubular boss of the doot knob. The spring-like nature of each of the k-nob catches 78 and 80 permits the button 79 thereof to be depressed until the knob .is moved into position for seating .of -t-he button 79 within the opening in the shank of the door knob.

Operation 'of the retractor slide .20 by rotation of the exterior door knob 63 may be prevented by la .turn-button 82 which is rotatably mounted within the hollow in- ,te-rior of :the outer end of the interior rollback S6. VThe turnbutton 82 yincludes a skirt 84 which is notched to receive .a pair of radial prongs 88 of a centrally apertu-red tu-rnbutton washer 99. The material of the skirt 84 is bent 4over the turnbu-tton washer 90 adjacent .the prongs -88 to retain the Iturn-button washer 9i) in engagement with the t-urnbutton 82, and one of the radial prongsVSS extends beyond the contines of the skirt 84 for engagement in a circumferentially oriented detent .slot 94 via a transversely extending cam slot 92 to lock the turnbutton 82 in its innermost position.

Inward movement of the turnbutton 82 to its innermost, locking position inwardly moves an elongated locking bar 96 which extends axially of the inte-rior rollback `56. The bar 96 includes a bent, outer extremity rotatably fitted within the central opening :in the turnbutton washer `9() for moving the bar 96 inwardly with the turnbutton 82, and a locking bar compression spring 98 is provided to outwardly bias the turnbutton 82 for outward movement of the locking bar 96 upon movement of the butto-n `82 out of the detent .slot 94. The locking bar compression spring 98 encompasses the locking bar 96 and is interposed between the turnbutton washer 90 and a locking bar guide 160 carried within the interior rollback 56.

The locking bar .guide 100 includes a center section l102 and a pair of substantially circular end sections constituting a pair of locking bar supports 104 and 106 which Iare centrally apertured 4to slidably accommodate the locking bar 96. The locking bar support 104 includes a prong 1-10 which is engaged between .the knob catch 78 and the end of an axially extending slot 112 (FIG. 2) of the interior rollback 56 to retain the guide t100 in position. The support 104 .is a seat for the adjacent end of the spring 98.

In order for the exterior rollback 58 to retract the retractor slide 20, there must be relative rotational movement between the exterior rollback 58 and the boss 64 of the exterior plate 26. -It is the function of the locking bar 96 to prevent such relative rotation between the eX- terior rollback 58 and the boss 64 so lthat a person may lock Ithe door from the inside by operation of the turnbutton S2.

For this purpose, the locking bar 96 is provided with an elongated shank `114 which is slid-ably, nonrotatably disposed through a longitudinally extending slot :116 in the retractor slide 20 intermediate the upper and lower pairs of anchor legs 42. The locking bar 96 includes a pointed head member 118 immediately behind which are formed a pair of spring receiving notches 120 for receiving one end of a locking bar dog compression spring |122, the other end of the spring 122 abutting against a substantially :rectangular locking bar dog 124 to bias the dog 124 away from the head member 118. The dog 124 is slidably carried upon the locking bar 96 and is limited in its outward movement by the bias of the spring 122 and in its inward movement by a pair of dog stops 126 and 128 constituted by a pair of lugs integral with and extending from the shank 114 of the locking bar 96. The -length of the sl-ot 116 through which the locking bar 96 is disposed is su'icient to permit longitudinal movement of the retractor slide 20 relative to the locking bar 96.

The locking bar dog i124 includes a vertically extending detent tab .130 which is radially or slidably disposable within a pair of longitudinally extending detent slots 132 and 134 provided, respectively, in the boss 64 of the exterior plate 26 and in the exterior rollback 58 `adjacent the interior end thereof. The detent slots .132 and 134 are -in alignment with each other when the retractor lslide 20 is in its extended position, `and move out of such alignment when the exterior rollback 58 is rotated one Way or the other to retract the retractor slide 20. In its inner or unlocked position closely adjacent the casing 12, the locking -bar detent tab 130 is located at the extreme inner end of the slot i132 in abutment with the face of the outer side plate 26. yIn this unlocked position, .the detent tab 130 is out of the s-lot 134 of the rollback 58 since the portion of .the rollback 58 defining the detent slot 134 .termina-tes outwardly of the detent tab 130 in its unlocked position. However, in its -outward or locked position, the detent tab i130 .is located in the outward end of the detent slot 132 and also Within the detent slot 134, thereby preventing relative rotation between the exterior rollback 58 and the boss 64.

As will be apparent, the locati-on of the detent tab in its locked position is accomplished by inward-ly depressing the turnbutton `82 to move the locking bar 96 inwardly. This moves the detent tab y130 into the outer end of the slot ,132 .and into the slot 134. The locked position of Ithe detent 4tab 130 is maintained by rotating the .inwardly depressed turnbutton 82 to move the radial prong 88 of the turnbutton washer 90 into the detent slot 94.

-In the locked position of the detent tab .130, it is noted that the interior rollback 56 may be rotated in either direction .so that the retractor slide 20 may be operated to open the door from the inside even though the exterior rollback 58 cannot be rotated to open the door from the exterior. However, lthe door can be opened from the exterior by operating the lock actuated rollback 72, as will be described hereinbeloW.

The lock actuated rollback 72 is adapted, as will be obvious to those skilled in the art, to receive a key operated lock cylinder 135, FIG. 2, which includes a rollback actuator 137. The rollback actuator 137 fits within a lock cylinder slot 136 provided in a lock cylinder end portion 138 of the rollback 72, and turning of the key rotates the rollback actuator 137 and consequently, the lock cylinder end por-tion 138. The rollback 72 rotates with its end portion 138 .to engage the cam 70 thereof with the upper one of the 4cam faces 40 of the retract-or slide 20. From the above description, it will be apparent that rotation of any one of the rollbacks, 56, 58, or 72 is effective to rearwardly move the retractor slide 20 against the bias of the retractor spring 50 to thereby -unlatch the main bolt `16.

The latch bolt case |14 in which the latch bolt 16 is sli-dably supported is an elongated body stamped or formed in any suitable manner from sheet material to provide a concave top wall 140 and a concave bottom wall 1142, the walls 140 and 142 being joined by a vertical side wall 144 Iand `a generally vertically disposed side wall 146. AS illustrated in FIG. 8 of the drawings, the edges of the sheet material from which the latch bolt case .14 is formed abut longitudinally along the wall 144, as indicated at 47, the edges preferably including a tongue and matching notch to permit separation of the edges when a retainer is inserted in the latch bol-t -case `14, and return of said edges to their original abutment when the retainer is fully seated in the latch bolt case 14 in the manner hereinafter described.

The side wall 146 includes a laterally, outwardly projected or olset side wall portion 148 which extends longitudinally of the latch bolt case 14 for slidably housing an auxiliary bolt 150. The side wall portion 148 opens through the forward open end of the case 14 into communication with a mating auxiliary bolt opening 149 provided in a vertically disposed, rectangular, composite face plate 152 which is disposable within a suitable opening therefor in the door withinwhich the lock set 10 is mounted. The side wall portion 148 is curved to form an internal concave channel or guideway for slidably receiving the adjacent curved surface of the auxiliary bolt 150. The face plate 152 also includes a latch bolt opening 154 through which the latch bolt 16 is slidable. A pair of slots 203 is formed in the side wall 62 on opposite sides of the side wall portion 148.

The latch bolt case 14 is readily connectable to and disconnectable from the slide housing 12 by a transversely slidable connection between the forward end of the housing 12 and the rearward end of the case 14. More par- 7 latch bolt case 14, and permits a latch bolt case 14 incorporating a dead latch or auxiliary bolt 150 to be readily substituted for a latch bolt case lacking this feature, or vice versa. That is, the slots 153 and the flanges 151 may be incorporated in various styles of the case 14 and housing 12 to permit ready interchangeability.

The main latch bolt 16 is of conventional design to provide the usual inclined face or surface 17 for slidably engaging against the strike plate 155 (FIGS. 4 and 5) of a doorframe (not shown) and has the latch bolt extension 18 secured to its inner end in the manner hereinafter described. The bolt extension 18 is of channel shape and extends longitudinally inwardly into the latch bolt case 14, being provided at its inner end with a pair of retractor tabs 156 constituted by a pair of inwardly turned flanges engageable by the T-head 46 of the bolt extension retractor 44 to retract the main latch bolt 16.

The bolt extension 18 includes a top wall 158, a bottom wall 160, and a vertically disposed side wall 162, the bolt extension 18 being open opposite the side wall 162 to dene an enclosure for receiving certain other components of the present lock set 10, as will be seen. The side wall 162 terminates forwardly or outwardly of the retractor tabs 156 in spaced relationship therewith so that the T-head 46 of the retractor slide 20 may be transversely slidably positioned within the tabs 156 against the forward vertical surfaces thereof for rearwardly moving the main latch bolt 16 upon retraction of the retractor slide 20. The bolt extension 18 has an elongated, longitudinal opening 166 provided in the side wall 162, for a purpose which will be described in greater detail below.

The latch bolt 16 and the bolt extension 18 are movable rearwardly independently of the retractor slide 20 upon the application of inwardly directed forces against the forward end of the latch bolt 16. This occurs, for example, upon engagement of the latch bolt 16 with the strike plate 155 when the door with which the lock set 10 is associated is closed. Such movement of the bolt extension 18 independently of the retractor slide 20 is provided for by including longitudinally extending slots 164 in the retractor slide 20, the retractor tabs 156 being slidably receivable within the slots 164 upon rearward or retracting movement of the bolt extension 18 when the retractor slide 20 is stationary.

The bolt extension 18 is maintained in operative relationship with the case 14 by a retainer 176 which is disposed through aligned, vertically extending slots 174` and 176 provided, respectively, in the side wall 144 and in the side wall portion 148 of the latch bolt case 14 and includes a head portion 178 which abuts against the outer surface of the side Wall 146. An end portion 180 of the retainer 17!) projects through the slot 176 in the side wall portion 148, securely fixing the retainer 170 in position across the case 14. The retainer 178 thus serves to maintain all of the `components of the dead latch in the case 14.

For ease of insertion of the retainer 170 into the slot 174 in the side wall 144, one end of the slot 17 4 terminates at line of abutment 147, between the adjacent edges of the case 14, and the relative dimensions of the slot 174 and the shank 172 of the retainer 170 are such that as the shank 172 is inserted in the slot 174, the shank 172, being somewhat wider .than the length of the slot 174, will cause the edges of the latch `bolt case 14 to separate. Formed on opposite sides of the shank 172 adjacent the head portion 178 are notches 179, The shank 172 of the retainer 170 is inserted in the slot 174 until the notches 17-9 are reached, at which time the ends of the slot 174 will drop into the notches 17 9 by spring action.

It should be pointed out that the retainer 170 .coopera-tes with the rear edge ofthe opening 166 in the bolt extension 18. Therefore, the retainer 170 serves to prevent undue extension of lthe main bolt 16 from the case 14 and retains the entire main bolt assembly or latch bolt means in operative relationship with the case 14.

CIK

rl`he dead latch or auxiliary bolt is constituted by a longitudinally extending body portion 182, a cylindrical body portion 184, and a longitudinally extending, reduced diameter cylindrical guide portion 185 whose inner extremity is slidably disposed through an arcuate guide opening 187 provided in the end portion 188 of the retainer 179. The body portion 182 is flat on one side and has a convex outer side surface which is complementary to the concave inner side surface of the channel or slideway formed by the side Wall portion 148 of the latch bolt case 14 and aligned with the surface of the cylindrical body portion 184. The body portion 182 and the cylindrical body portion 184 are freely and longitudinally slidable within the side wall portion 148, and in its most extended position the body portion 182 projects outwardly beyond the face plate 152 a distance substantially equal to the distance which the main latch bolt 16 projects beyond the face plate 152, as best illustrated in FIG. 2 of the drawings, The cylindrical body portion 184 and the fiat surface of the body portion 182 dene a cam shoulder 187.

The auxiliary bolt 15) is biased toward its outer or projected position by an auxiliary bolt compression spring 188 surrounding the guide portion 185, and the spring 188 is engaged at one end against the retainer 170 and at the other end against a shoulder 198 formed by the juncture of the cylindrical body portion 184 and the guide portion 185. The outer end of the auxiliary bolt 150 is depressed or moved inwardly by engagement with the strike plate and, since the keeper or opening in the strike plate 155 is only large enough to accommodate the main bolt 16, the auxiliary bolt 150 is normally held by the strike plate 155 in retracted or inward position when the door with which the lock set 10 is associated is closed.

However, when the main latch bolt 16 is moved inwardly by engagement with the strike plate 155 or by retraction of the retractor slide 20, the auxiliary bolt 150 is moved inwardly with the main latch bolt 16 as a unit by reason of the engagement between the shoulder 186 .of the auxiliary bolt 150 and the inner end 3,80 of the main latch bolt 16.

A deadlocking dog 196 is mounted for pivotal movement within the hollow interior of the bolt exten-sion 18 and is generally C-shaped in configuration, being constituted by substantially horizontally oriented and longitudinally extending parallel side plates 198 and 288, spaced apart from each other. The plates 198 and 208 are joined at the front ends thereof by a transverse, vertically disposed plate 2182, on which is formed a protruding inclined tongue 204.

At the rear ends of the plates 198 and 288 outwardly projecting prongs 286 and 208, respectively, are formed, the prongs 286 and 28.8 being disposed so as to be received in bores 216 and 212 in top wall 158 and bottom wall 168, respectively, of the bolt extension 18 so as to hinge the deadlocking dog 196 within the hollow interior of the bolt extension 18.

Formed on the edges of plates 198 and 200, respectively, adjacent the transverse plate 282, are dogs 214 and 216 which are disposed so asto be received in the slotted openings 283 in the side wall portion 148 of the side wall 146 of the latch bolt case 14. The edges of the opening 283 provide d-ogging surfaces.

As best illustrated in FIG. 9 of rthe drawings, the inner end 308 of the main latch bolt 16 is hat and incorporates a cavity 302, said cavity 302 being positioned to receive the tongue 284 on the deadlocking dog 196. Formed in the cavity 302 is a boss 394, which provides a seat for a deadlocking dog spring and a compression spring hereinafter described.

Formed on the top and bottom surfaces -of the main latch bolt 16 are cavities 306 and 388, respectively, open to the inner end 388 of the main latch bolt 16. A trans- 9 verse bore 310 extends from the cavity 306 to the cavity 308.

The top wall 158 and the bottom wall 160 of the 'latch bolt extension 18 incorporates ytongues 312 and 314, respectively, at the outer end of the bolt extension 18 adapted to be slidably received in the cavities 306 and 308 of the main latch bolt 16. Aligned elongated openings 316 and 318 are formed in the tongues 312 and 314 respectively, for alignment with the bore 310 in the main latch bolt 16.

The latch bolt extension 18 is connected to the main latch bolt 16 Iby means of a roll pin 320 which is driven through the aligned lbores 316, 310, and 318. The pin 320 is firmly seated in the bore 310, but is moveable in the openings 316 and 318 -to permit lost rnotion between the main latch bolt 16 and the bolt extension 18.

A deadlocking dog spring 340 of U-conguration has arms 342 and 344 extending rearwardly in the latch bolt extension 18 and inclined to serve as leaf springs bearing on the plates 198 and 200, respectively, of the deadlocking dog 196 to bias the deadlocking dog 196 toward the side wall portion 148 of the latch bolt case 14, and thus to urge the dogs 214 and 216 of the deadlocking dog 196 toward the slotted opening 203 in the side wa'll portion 146. The U-shaped deadlocking dog spring 340 has an upwardly extending inclined plate 348 formed thereon, and an aperture 349 is provided in the plate 348 which is received in the cavity 302 in the latch bolt 16, the aperture 349 being adapted to receive the boss 304 in the cavity 302.

A deadlatch bolt spring seat 360 has a tiat plate or body member 362 and rearwardly directed legs 364 and 365 formed on the sides of the body member 362 intermediate -the ends thereof which engage the plates 198 and 200, respectively, of the deadlocking dog 196. One end 366 of the body member 362 is inserted in an elongate, rectangular opening 166 of the side wall 162 of the bolt extension 18 and abuts on the rearward end thereof. Adjacent the 4other end of the plate 362 an opening 367 is provided to slidably receive and support the reduced diameter guide portion 185 of the -auxiliary bolt 150, the plate 362 also serving as a rear seat for the spring 188. Adjacent the end 366 of -the plate 362 a boss 368, projecting forwardly in the bolt extension 18, serves as a seat for one end of a compression spring 370, the other end of the compression spring 370 being seated on the boss 304 on the main latch bolt 16 externally of the plate 348 of the deadlocking dog spring 340.

The deadlatch bolt spring seat 360 is retained in position within the latch bolt extension 18 by abutment against the shank 172 of the Iretainer 170.

In summary, the operation of the lock set 10 of the present invention is as follows:

Under normal circumstances, upon closure of the door with which the lock set 10 is associated, as illustrated in FIG. 4 of the drawings, the main lbolt 16 is extended into the keeper in the strike plate 155, while the auxiliary bolt 150 is depressed by its labutment on the strike plate 155, so that the deadlocking dog 196 is free to assume its dogging position. In this situation, the biasing action of the compression spring 370, acting on the otset plate 348 of the deadlocking dog spring 340, will lift the arms 342 and 344 of the deadlocking dog spring 340 -to pivotal'ly bias the deadlocking dog 196 toward the side wall portion 146 of the latch bolt case 14 and position the dogs 214 and 216 of the deadlocking dog 196 in the slotted opening 203 so as to prevent forcible retraction of the main bolt 16.

If an attempt is made to forcibly retract the main bolt 16, `as by impingement of an instrument, such as a knife blade, against said bolt, force being applied in the direction of the arrow shown in FIG. 5 of the drawings, the bolt 16 (except for lost motion between the bolt 16 and the bolt extension 18) will be electively blocked against retraction by the impingement of the tongue 204 on the inner end 300 of the bolt 16.

If it is desired to open the `door from the interior, the interior door knob 61 is rotated in either direction, thus rota-ting the interior rollback 56 to engage one of its retractor cams 54 with one of the cam faces 38 of the retractor slide 20. The retractor slide 20 is then retracted against the bias ot the retractor spring 50, and the T-head 46 of Ithe slide 20 engages the inner surfaces of the retractor tabs 156 of the bolt extension 18, retracting the bolt extension 18 and, after a lost motion interval, retracting the bolt 16.

The case 14 and the retainer 170 are the immovable parts of the total assembly. The spring 370, which is the main bolt spring, is seated between the main bolt 16 and the spring seat 368 and its bias is increased by the inward movement of the bolt 16, The bias of the spring 370 imposed upon and transmitted through the dead locking dog -spring 340 always tends to force the dogs 214 and 216 outwardly so that, when said dogs are juxtaposed to the slots 203, they will extend through the side of the case 146 to ldog the main sbolt 16 against unauthorized retraction into the case 14.

The cam 186 provided on the auxiliary bolt 150, by its impingement on the tongue 204 of the locking dog 196, maintains the dogs 214 and 216 of the dead locking dog 196 out of engagement with the openings 203 when the main bolt 16 and auxiliary bolt 150 are simultaneously depressed, as when they irnpinge on an associated strike during the closing of the door.

The pivot points constitu-ted by the prongs 206 and 208 on the deadlocking dog 196 are disposed to one side ofthe centerline of the latch and, as best shown in FIG. 4 of the drawings, the prongs 206 and 208 of the locking dog 196 extend through the slots 203 in the case 14, but Without actually clogging the bolt 16.

When retracting the main bolt 16 with the components `located in the attitude of FIG. 4 of `the drawings, the retractor slide 20 is urged inwardly by rotation of the associated knobs and the angular moment of force causes the deadlocking dog 196 to rotate and slidably disengage the dogs 214 and 216 from the slots 203.

In the position of the components shown in FIG. 5 of the drawings, the surface 302 of the main bolt impinges on the tongue 204 ofthe locking dog 206 thereby wedging the dogs 214 and 216 against the edges of the slots 203 creating a securing dogging connection. Under normal conditi-ons of use, the latch bolt 16 would not be retracted when pressure is applied to it, as indicated in FIG. 5 of the drawings.

However, in some instances, such as warped doors, or too shallow a pocket for the bo-lt 16 behind the strike 155, the dogs 214 an-d 216 may be wedged into a solid dogging position. The slots 316 and 318 in the outer end of the bolt extension 18 permit the wedging action of the locking dog 196 when pressure is imposed on the bolt 16, but also permit momentary release of that pressure when the bolt is withdrawn -by knob rotation through the retractor slide 20. The momentary relief of wedging pressure by drawing the bolt extension 18 inwardly away from the bolt 16 permits the withdrawal of the dogs 214 and 216 from the slots 203. This frees the bolt 16 for retraction.

I claim:

1. In a dead latch, the combination of: a case having a side dogging opening therein; a main bolt mounted for reciprocation with said case; a channel-shaped latch bolt extension connected to said latch bolt; a dog pivotally 4mounted -in the latch bolt extension at one side of the central longitudinal axis of said ease, said case side dogging -opening being at the other side of said case central longitudinal axis from said one side; and a spring engageable with the dog to bias the dog angularly pivotally to a dogging position in said opening whereby movement of said extension will impose a force on the pivotal mounting of said dog to oppositely angularly pivot i-t and permit it to be free from its clogging position.

2. In a dead latch mechanism, the combination of: a housing having a dogging opening therein; a latch bolt mounted for reciprocation in said housing; a latch bolt extension secured to said latch bolt, said extension defining an enclosure; a dog pivotally mounted upon s'aid extension and in said enclosure at one side of the central longitudinal axis of said housing, said dog having pivot points on the opposite sides thereof engageable in opposite portions of said latch bolt extension; and a spring engageable with said dog to bias said dog to a dogging position in said opening whereby when said latch bolt extension is withdrawn into said housing an angular moment of force will be imposed upon lsaid dog to withdraw said dog from said dogging position in said ope-ning.

3. In a dead latch mechanism, the combination of: a housing having a dogging surface thereupon; a main bolt mounted for reciprocation in said housing; a latch bolt extension secured to said latch bolt; a dog pivotally mounted in the latch bolt extension by pivot points on said dog engageable with said extension at a location displaced laterally from the longitudinal central axis of said housing; a first spring engageable with said dog to bias said dog to a dogging position against said su-rface, said first spring having a mounting plate for supporting it on said bolt; a compression spring disposed longitudinally in said latch bolt extension and 'se-ated at one end on said offset mounting plate so ,as to bias said first spring against said dog to momentarily urge said dog into engagement with said dogging surface when Said main bolt is extended from said housing; and a spring seat in said latch bolt extension for seating the other end of the compression spring so that when a retractive force is imposed on said extension said dog will be subjected to an angular moment of force through said pivot points cause of relative movement between said extension and said pivot points to withdraw said dog from engagement With said surface.

4. A latch bolt mechanism as defined in claim 3, inclu-ding a retainer extending transversely of the housing so as to retain said latch bolt extension within said housing.

5. In a dead latch mechanism, the combination of: a housing having a dogging surface, said housing being split longitudinally and having opposed slots therein; a latch bolt slidably mounted in said housing; a hollow latch bolt extension connected to said latch bolt; a dog piv-otally mounted in said latch bolt extension by pivot points on said dog engageable with said extension at a location displaced laterally from the longitudinal central axis of said housing; a first spring engageable with said dog to bias said dog to a dogging position on said surface, said spring having an offset mounting plate mounting said first spring on sai-d latch bolt; a compression spring disposed longitudinal-ly in said latch bolt extension and seated at one end on said offset mounting plate to bias said first spring against said dog; a spring seat in said latch bolt extension for seating the other end of said compression spring; and a retainer hav-ing laligned notches on its opposite edges, said retainer being transversely disposed in opposed slots in said housing to retain said latch bolt extension within said housing, one of said slots in said housing being contiguous to said split in said housing, the relative dimensions of said slot and said retainer beng such that upon insertion of said retainer in said slot, said housing will separate .at said split to laccommodate said retainer in said slot, said separation continuing until said notches in said retainer are aligned with said one slot, whereupon said split Will close to seat said housing in said notches` 6. In a dead latch mechanism, the combination of: a housing having a Vdogging opening therein; a latch bolt slidable in said housing; `a hollow latch bolt extension secured to said latch bolt; a dog pivotally mounted in said latch bolt extension by pivot points on said dog engageable with said extension at a location displaced laterally from the longitudinal central axis of said hous-ing, said dog having a dogging portion engageable with said opening Iand a bolt dogging tongue thereupon; a first spring engageable with said dog to bias said dog to a dogging position in said opening, said spring having an off-set mounting plate for mounting it on said latch bolt; a compression spring disposed longitudinally in said latch bolt extension and seated at one end on said offset mounting pla-te .to bias said first spring against said dog; aV

spring seat in said latch bolt extension for seat-ing the other end of said compression spring; an auailiary bolt slidably disposed in said housing, said auxiliary bolt being movable inwardly upon inward movement of said latch bolt; and a cam on said xauxiliary bol-t disposed to cam said dogging tongue into dogging position with said latch bolt.

7. In a dead latch, the combination of: elongate latch bolt means including la latch bolt; a housing adapted to slidably receive and 4retain said latch bolt means and permit movement of said latch bolt means between a projected position and a retracted position relative to said housing; a dog pivotally mounted on said latch bolt means for movement to a pivoted angular dogging position by pivot points engaging opposite portions of said latch bolt means .to one side of the central longitudinal axis of said hous-ing and having dogging portions engageable with said housing at the other side of said housing central longitudinal anis and a dogging tongue engageable With said latch bolt; a spring engageable with said dog to bias said dog pivota-lly 1an-gular toward dogging position; and an auxiliary bolt mounted in said housing adjacent said latch bolt.

8. In a latch bolt mechanism, the combination of: a housing having a dogging opening therein; a latch bolt slidable in said housing; -a latch bolt extension secured to said latch bolt; a dog pivotally mounted in said latch bolt extension by pivot points engaging opposite portions of said latch bolt extension to one side of the central longitudinal axis of said housing and having dogging portions engageable with said housing and a dogging tongue engageable with said latch bolt; a rst spring engageable with said dog to bias said dog to a dogging position in said opening, said spring having an offset mounting plate for mounting said first spring on said latch bolt; a compressi-on spring disposed longitudinally in said latch bolt extension and seated at one end on said offset mounting plate to bias said rst spring against said dog; a spring seat in said latch bolt extension for seating the other end of said compression spring; a retainer disposed transversely of said h-ousing to restrict the rearward movement of said latch bolt extension with-in said housing; means for retracting said latch bolt and said latch bolt extension, said means including a retractor slide engageable with said latch bolt extension for inward movement of said latch boil-t extension; and an auxiliary bolt slidably carried by said housing, said auxiliary bolt mounted in said housing adjacent said latch bolt.

References Cited by the Examiner UNITED STATES PATENTS 2,293,645 8/1942 Falk 70-151 2,343,249 3/1944 Spinello 70-150 2,558,509 6/1951 Cerf 292-153 2,804,327 8/1957 Williams et al. 292-169 3,186,747 6/l965 Hamm et al. 292-169 EDWARD C. ALLEN, Primary Examiner. RICHARD E. MOORE, Examiner.

I, RP MOSES, StYiSant Examiner. 

2. IN A DEAD LATCH MECHANISM, THE COMBINATION OF; A HOUSING HAVING A DOGGING OPENING THEREIN; A LATCH BOLT MOUNTED FOR RECIPROCATION IN SAID HOUSING; A LATCH BOLT EXTENSION SECURED TO SAID LATCH BOLT, SAID EXTENSION DEFINING AN ENCLOSURE; A DOG PIVOTALLY MOUNTED UPON SAID EXTENSION AND IN SAID ENCLOSURE AT ONE SIDE OF THE CENTRAL LONGITUDINAL AXIS OF SAID HOUSING, SAID DOG HAVING PIVOT POINTS ON THE OPPOSITE SIDES THEREOF ENGAGEABLE IN OPPOSITE PORTIONS OF SAID LATCH BOLT EXTENSION; AND A SPRING ENGAGEABLE WITH SAID DOG TO BIAS SAID DOG TO A DOGGING POSITION IN SAID OPENING WHEREBY WHEN SAID LATCH BOLT EXTENSION IS WITHDRAWN INTO SAID HOUSING AN ANGULAR 